In the South West region, the Nationals have preferenced Greens candidate Diane Evers above Liberals Wade De Campo, Robyn McSweeney, Tony Norment and Heather Reid, but Liberal Steve Thomas has been placed behind the four Nationals candidates.

WA Nationals spokesman Nathan Quigley downplayed the significance of the move, which comes after a preference deal between the Liberals and One Nation emerged.

Mr Quigley said his party had a lot in common with the Shooters and Fishers and also expected the Liberal Democrats and Australian Christians to be competitive.

"Our votes will go towards getting one Liberal elected in each region, which they haven't done for us," he told AAP.

"They've got our first candidates below other candidates everywhere else .... and then we go to the Shooters and Fishers after that.